Embodiments of the present invention generally relate to an apparatus and method for analysis of engines. More particularly, the present invention relates to an apparatus and method to fill-in an ignition event when one (or more) ignition event is missing.
Conventional combustion, reciprocating engines are widely used as automotive engines. A conventional engine (single-cycle, two-cycle and others) is typically composed of an engine or cylinder assembly having one or more cylinders therein. A piston is slidably disposed in the cylinder and moves reciprocally within the cylinder. A cylinder head at one end of the cylinder completes the cylinder assembly. The cylinder head typically contains the valves (intake and exhaust) and the spark plug. The spark plug typically ignites a pre-mixed fuel that is injected by the intake valve into a combustion chamber and helps to define an ignition event.
Should an ignition event not occur or the cylinder misfires, it can reduce the power output of the engine, can cause low fuel economy, increased emissions and poor performance. Engine analyzers are used to analyze the performance of internal combustion engines. Engine tests can include detection of rotation-per-minute fluctuations of engine input, exhaust pipe temperature changes, relative temperature differences among the exhaust ports, rotational torque variations, exhaust pressure pulsing, and abnormal content of exhaust gases.
A conventional digital analyzer can convert analog signals to digital signals for display on an oscilloscope, which displays snapshots of discrete portions of the signals as waveforms. In the case of multiple cylinders, waveforms showing the primary and the secondary ignition voltages are displayed. The voltages are acquired from a primary and a secondary lead that are connected to an ignition coil. A synch probe may be attached to the first cylinder so that the analyzer can identify the cylinders (by knowing where in the sequence the first cylinder is) and determine the firing order of the cylinders. The analyzer can display sweeps, such as an engine sweep or a fixed time sweep. Engine sweeps can display a single cylinder ignition event or a complete cycle of ignition events. Additionally, the engine sweep may be displayed as cylinder, parade, or raster. Cylinder sweep displays only a single cylinder waveform while the parade and raster display all the cylinders but in a horizontal progression or stacked vertically on top of one another, respectively. The fixed time sweep displays a fixed period of time in which the data is to be collected and shown as determined by a user.
Regardless of which sweep the analyzer displays, the analyzer can show false readings when a cylinder misfires. For example, the engine may have four cylinders and are designed to fire in order of 1, 2, 3, and 4. If the second cylinder misfires (or not fire at all), then the data gathered by the analyzer may be skewed. The analyzer will pick up the signal from the first cylinder""s ignition event, but because the second cylinder does not fire, the data from the first cylinder can be extended until the third cylinder""s ignition event. When the third cylinder""s ignition event is collected, the analyzer may think that the second cylinder has fired so the data for the third cylinder will be off and the same for the fourth cylinder (analyzer thinks the third cylinder""s ignition event, when it is really the fourth cylinder""s ignition event). If the analyzer displays bad data, then it can take longer to locate and fix the correct cylinder, leading to unnecessary costs to the consumer.
Therefore, there is a need for an apparatus and a method to compensate or fill-in for the misfired ignition event so that the analyzer can display accurate data.
Embodiments of the present invention generally provide for an apparatus and method to allow the analyzer to collect the correct data and store it for correct display on the oscilloscope even if an ignition event does not occur.
In one embodiment, a method to fill-in an ignition event in an engine is provided and can include determining an engine period of the engine, determining a cylinder time from the engine period, determining a predictive window time, and analyzing the cylinder ignition for a time period to determine if a fill-in signal should be injected. The engine period can be the period of an engine cycle of the engine. The cylinder time can be calculated by dividing the engine period by the number of cylinders. The predictive window time may be related to the r.p.m of the engine. Analyzing the cylinder ignition event can further include starting the time period, determining if the ignition event occurred at the end of the time period, and injecting the fill-in signal if no ignition event occurs by the end of the time period. The time period can be the predictive window time plus the cylinder time or can be the cylinder time, when the preceding event included injecting the fill-in signal.
A fill-in apparatus for an engine is also provided and can include an engine period determiner that can calculate an engine period, a cylinder time determiner that can calculate a cylinder time, a delayed time determiner that can calculate a predictive window time; and a pseudo cylinder injector to inject a pseudo cylinder signal, wherein the injector and the determiners are in communication with each other. The pseudo cylinder injector can inject the pseudo cylinder signal based on a time period. The fill-in apparatus can start the time period, and injects the pseudo cylinder signal if there is no ignition event at that cylinder by the end of the time period. The cylinder time determiner can calculate the cylinder time by dividing the engine period by the number of cylinders of the engine. The delayed time determiner may calculate the predictive window time based on the r.p.m of the engine. The time period can be the cylinder time when the previous event included injecting a pseudo cylinder signal. The time period can be the predictive window time plus the cylinder time.
A fill-in system for an engine that can include a means for determining an engine period of the engine, a means for determining a cylinder time from the engine period, a means for determining a predictive window time, and a means for analyzing the cylinder ignition for a time period to determine if a fill-in signal should be injected. The means for determining the engine period can calculate the engine period based on the engine cycle. The means for determining the cylinder time can calculate the cylinder time by diving the engine period by the number of cylinders. The means for determining the predictive window time can calculate the predictive window time based on the r.p.m of the engine. The means for analyzing the cylinder ignition can inject the fill-in signal if the ignition event does not occur by the end of the time period. The time period can be a cylinder time or a delayed time plus the cylinder time.
In a further embodiment of the invention, a signal generator can include a controller that calculates an engine period, a cylinder time, a predictive window time for an engine, and a signal injector that can inject a pseudo cylinder signal if an ignition event does not occur at a cylinder of the engine, wherein the controller communicates with the signal injector.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.